Cronbachs Alpha

Cronbachs alpha is one of the most widely used measures of reliability or survey data in the social and organizational sciences.  When we need to test the internal consistency (reliability) of multiple Likert questions in a survey (scale), It is the best tool. Internal consistency describes the extent to which all the items in a test measure the same concept or construct and hence it is connected to the inter-relatedness of the items within the test.  To ensure the validity, internal consistency should determine before conducting a test.  By estimating the reliability we can identify the quantum of error in a test.  “It is an indication of how well the different items complement each other in their measurement of different aspects of the same variable or quality” (Litwin, 2003).

Lee Joseph Cronbach was an American educational psychologist who contribute this reliability test.

Internal Consistency and Cronbachs Alpha

Internal Consistency is the measure of reliability. It is the consistency of the result derived in a test , ensuring that the various items measuring the different constructs deliver consistent scores. Typically in research we usually want to measure constructs rather than particular items. So we need to identify whether the items have a huge influence on test score and the conclusions there of Internal consistency reliability depicts well a test addresses different constructs and delivers reliable scores. Internal consistency give an idea about how well the survey or test items are designed to measure the construct. A construct is an underlying theme under study.

The theatrical value of alpha ranges in between zero and one. Values closer to one indicate a higher internal consistency; values closer to zero indicate a lower internal consistency.

Here this video explains How to test the internal consistency of a scale using Cronbach’s alpha using Microsoft Excel and SPSS